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When a thunderstorm's updraft interacts with this gust front, the gust front's horizontal spin can be tilted into the vertical and stretched. A gust front marks the leading edge of a thunderstorm's outflow winds, featuring winds spinning about a horizontal axis, like rolling a pencil across your desk.
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In simple terms, the theory goes like this. "Outflow surges have been identified by Hastings as a key component to mesocyclone intensifications observed after cell mergers." "The outflow surge observed after the Moore supercell single-cell merger appears to be consistent with numerical simulations by Hastings," said Wade. Specifically, Wade noted that EF4 and EF5 damage, shown by red and purple contours in the map below, occurred after this cell merger and subsequent outflow surge. "Combining damage surveys with the radar characteristics of the Moore supercell indicate the Moore tornado intensified after the cell mergers," said Wade. The supercell's hook echo then became more pronounced, with a distinct debris ball signature (circular area of red/purple reflectivity headed toward Moore), indicative of wind-lofted tornado debris. Wade noted an outflow surge - a surge of stronger winds associated with the supercell's rear-flank downdraft - occurred just after supercell merged with the decaying thundershowers. Highlighted by the yellow arrow is a decaying cluster of weak thundershowers moving northeast toward the supercell. (hereafter, NWS-Norman), you can see the Moore supercell with a pronounced hook echo first developing as it passed northwest of the town of Newcastle. In the radar loop above from the National Weather Service in Norman, Okla. Wade was presenting findings from an investigation of supercell mergers and other storm-scale interactions in recent tornado outbreaks with fellow UAH researchers Todd Murphy and Dr. This was the question posed by Ryan Wade, a University of Alabama-Huntsville (UAH) severe weather researcher, at the annual meeting of the National Weather Association in North Charleston, S.C. tornado on turned violent thanks to adjacent, non-severe thundershowers?